Amyotrophic lateral sclerosis (ALS): symptoms, causes and treatments

The amyotrophic lateral sclerosis (ALS) or “disease Lou Gehrig ” is a neurological disease degenerative a progressive cusp that affects the motor neurons that are located in the brain and spinal cord (The Journal American Medical Association, 2007).

The degeneration of this type of neurons that are in charge of transmitting the orders of the voluntary movements to the muscles causes that the capacity of the brain to initiate the motor execution is lost. Therefore, patients begin to show progressive muscle atrophy and develop severe paralysis (Foundation Miguel Val’s, 2016).

Amyotrophic Lateral Sclerosis

In addition to motor impairment, impaired ability to articulate language, swallowing or breathing, recent studies have shown that  this type of disease may also be associated with dementia front-temporal processes, showing cognitive and behavioral alterations in  individuals (Miguel Val’s Foundation, 2016).

It is a disease with a progressive course, invariably fatal (National Institute of Neurological Disorders and Stroke, 2013). Despite this, patients’ quality of life, and even survival time, can vary significantly depending on the type of medical performance used (Orient-Lopez et al., 2006).

Prevalence of amyotrophic lateral sclerosis

In many cases, amyotrophic lateral sclerosis is considered a rare or minor type disease. The number of people suffering from this disease is between 6 and 8 people per 100,000 inhabitants. Despite this, we must bear in mind that the incidence of the disease is 1-3 new cases per 100,000 inhabitants each year (Foundation Miguel Val’s, 2016).

The statistical estimates put the number of cases of amyotrophic lateral sclerosis in Spain in approximately 4,000, while in the world it  is estimated in about 350,000 cases (Foundation Miguel Val’s, 2016).

ALS is more prevalent in men than in women, approximately 1.2-1.6: 1, and is usually present in individuals with adulthood. It is estimated that the mean age of onset is about 56 years of age, and that presentation is scarce before age 40 or after 70 (Orient- Lopez et al., 2006). However, there are cases of the disease in people 20 to 40 years old (Amyotrophic Lateral Sclerosis Association, 2016)

On the other hand, the average duration of the disease is usually three years, reaching a survival of more than 5 years in 20% of those affected and more than 10 years in 10% of these patients (Orient-Lopez et al., 2006).

Generally more than 90% of cases of ALS occur randomly without presenting a clearly defined risk factor. Patients usually do not have an inherited history of the disease or are not considered to be at high risk for ALS. Only 5-10% of cases of ALS are inherited (National Institute of Neurological Disorders and Stroke, 2013).

Definition of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neuromuscular disease that was discovered in 1874 by Jean-Martin Charcot. He described it as a type of disease in which the nerve cells that control the movement of the voluntary musculature, motor neurons, progressively diminish their efficient functioning and die, leading to weakness followed by severe motor atrophy (Paz Rodriguez et al., 2005).

Also Read: Cerebral Palsy: Symptoms, Causes, Treatments

Motor neurons are a type of nerve cell that can be located in the brain, brain stem and spinal cord. These motoneurons serve as centers or units of control and linkage of the information flow between the voluntary body muscles and the nervous system (National Institute of Neurological Disorders and Stroke, v).

Information from motor neurons located at the brain level (called upper motor neurons) are transmitted to  motor neurons located at the level of the spinal cord (called lower motor neurons) and from there, the information flow is sent to each  particular muscle (National Institute of Neurological Disorders and Stroke, 2013).

Thus, in amyotrophic lateral sclerosis, degeneration or death will occur in both upper motor neurons and lower motor neurons  National Institute of Neurological Disorders and Stroke, 2002) and will thus prevent essential chemical and nutrient messages which  require the muscles to function properly do not reach the muscle areas (Paz-Rodriguez et al., 2005).

Due to inability to function, muscles will progressively show weakness, atrophy, or contractions (fasciculation’s) (National Institute of Neurological Disorders and Stroke, 2013).

Specifically, in this pathology there is a specific definition of each of its terms (Paz-Rodriguez et al., 2005):

  • Sclerosis: means “hardening”. Specifically, it means hardening of tissues when nerve pathways disintegrate
  • (Paz-Rodriguez et al., 2005).
  • Lateral: implies the notion of “side”, and refers to the nerves that run bilateral in the spinal cord (Paz-Rodriguez et al., 2005).
  • Amyotrophic: this term is often used as “related to muscular atrophy”, it is a severe degeneration of motor neurons that

Will cause a progressive paralysis of the muscles involved in movement, speech, swallowing or breathing (Paz-Rodriguez et al.


Amyotrophic lateral sclerosis symptoms

In many instances, the onset may be very subtle, showing signs so slight that they are often overlooked (National Institute of Neurological Disorders and Stroke, 2013).

Early symptoms may include contractions, cramps, muscle stiffness, weakness, impaired speech, and difficulty chewing (National Institute of Neurological Disorders and Stroke, 2013). Specifically, they may appear (Amyotrophic Lateral Sclerosis Association, 2016):

  • Muscle weakness in one or more of the following areas: upper limbs (arms or hands); lower limbs (specifically legs); of the articulator muscles of language; muscles involved in swallowing or breathing.
  • Tics or muscle cramps, which most commonly occur on the hands and feet.
  • Inability to use arms or legs.
  • Deficits in language: like “swallowing the words” or difficulty projecting the voice.
  • In later stages: shortness of breath, difficulty in breathing or swallowing.

The parts of the body that will be affected by the first symptoms of lateral sclerosis amyotrophic will depend on which muscles of the body are damaged first (National Institute of Neurological Disorders and Stroke, 2013). So the initial symptoms usually vary a lot from one person to another. Other.

In some cases they may experience walking difficulties, difficulty walking or running as the main manifestation, while others may present difficulties when they need to use a limb, problems lifting or picking up objects, or in other cases presenting with stuttering (Amyotrophic Lateral Sclerosis Association, 2016).

Progressively, the involvement in a muscle or limb area extends contra lateral. Thus, the deficit becomes symmetrical in the four extremities. In a time no longer than one year, the great part of the patients presents tetra paresis with a degree of greater or lesser gravity (Orient-Lopez et al., 2006).

Gradually, the evolution of the disease will affect the bulbar level, producing an alteration of the musculature of the neck, face, pharynx and larynx. A severe alteration of the articulation of words and of swallowing begins, in its beginning of liquids and progressively also of solids (Orient-Lopez et al., 2006).

In the later stages of the disease, when the disease is present in advanced stages, weakness and muscular paralysis extend to the  respiratory muscles (Orient-Lopez et al., 2006), patients lose their ability to breathe autonomously and will be necessary the use of an  artificial respirator to maintain this vital function (National Institute of Neurological Disorders and Stroke, 2013)

In fact, respiratory failure is the most prevalent cause of death in people with amyotrophic lateral sclerosis, while other causes such as pneumonia are less prevalent (The Journal American Medical Association, 2007).

In most cases, within 3 to 6 years after the initial presentation of the symptoms, the patient’s death usually occurs, although in some cases they often live several decades with this pathology (The Journal American Medical Association, 2007).

Due to the fact that amyotrophic lateral sclerosis mainly affects motor neurons, somatosenrial, auditory, gustatory and olfactory function will not be affected. Also, in many cases, no affectation of ocular mobility and sphincter function will occur (Amyotrophic Lateral Sclerosis Association, 2016).

Causes of Amyotrophic Lateral Sclerosis

The specific causes of amyotrophic lateral sclerosis are not exactly known. Genetic factors related to three autosomal dominant transmission loci (21q22, 9q34 and 9q21) and two autosomal recessive transmissions (2q33 and 15q15-q21) have been identified in cases where the disease is inherited, Lopez et al., 2006).

However, a number of causes have also been proposed as potential etiologic factors for amyotrophic lateral sclerosis: environmental,  exposure to heavy metals, viral infections, prison diseases, autoimmune factors, paraneoplastic syndromes, etc., although there is  no irrefutable evidence of their role (Orient-Lopez et al., 2006).

Some of the path physiological mechanisms that have been identified in relation to this pathology are (Foundation Miguel Val’s, 2016):

  • Reduced availability of neurotrophic factors
  • Disorders of calcium metabolism
  • Excitoticity due to excess glutamate
  • Increased nenuroinflammatory response
  • Changes in the cytoskeleton
  • Oxidative stress
  • Mitochondrial damage
  • Protein aggregation
  • Transversal disturbances
  • Other factors.

Because of this initial description that emphasizes the indicia of genetic factors; clinical investigations have proposed several types of amyotrophic lateral sclerosis (Amyotrophic Lateral Sclerosis Association, 2016):

  • Sporadic: it is usually the most prevalent form of amyotrophic lateral sclerosis. Specifically, in the United States it is around 90-95% of all cases. However, it is thought that endogenous factors (metabolic and genetic) and exogenous factors (environmental, related to the individual’s lifestyle) are involved (Foundation Miguel Val’s, 2016).
  • Familiar: usually due to a dominant genetic inheritance and occurs more than once in a family line. It represents a small number of cases, around 5-10%. The implication of some genes has been described: SOD1, Asian, VAPB, TARDBP, FUS, Sachem, OPTN, VCP, ANG, UBQLN2, and C9ORF72 (Miguel Val’s Foundation, 2016).
  • Guamanian: Different studies have observed a high incidence of amyotrophic lateral sclerosis in Guam and territories in Pacific Trust in the 1950s. (Amyotrophic Lateral Sclerosis Association, 2016).


Amyotrophic lateral sclerosis is pathology difficult to diagnose. There is currently no single test or procedure to perform the definitive diagnosis of the disease (Amyotrophic Lateral Sclerosis Association, 2016).

Therefore, the diagnosis of this type of pathology is fundamentally clinical and is based on the demonstration of the presence of signs and symptoms of motor neuron involvement, such as weakness, atrophy or fasciculation (Orient-Lopez et al., 2006).

A complete differential diagnosis should include most of the procedures listed below (Amyotrophic Lateral Sclerosis Association, 2016):

  • Electromyography (EMG) and nerve conduction @nalysis (NCV).
  • Blood and urine tests should include serum protein electrophoresis, @nalysis of thyroid and parathyroid hormone levels, and detection of heavy metals.

There are several diseases that can cause some of the symptoms that occur in ALS. Because many of these are treatable, the Amyotrophic Lateral Sclerosis Association (2016) recommends that a person who has been diagnosed with ALS seek a second opinion with a skilled professional to rule out possible false positives.


Currently, experimental studies have found no cure for ALS. So far no cure has been found for ALS (National Institute of Neurological Disorders and Stroke, 2013)

The only drug that has proven a delay in this pathology is Relizon (Amyotrophic Lateral Sclerosis Association, 2016). It is thought that this drug reduces damage in motor neurons by decreasing the release of glutamate (National Institute of Neurological Disorders and Stroke, 2013)

In general, treatments for ALS are aimed at relieving symptoms and improving the quality of life of patients (National Institute of Neurological Disorders and Stroke, 2013).

The most current studies show that comprehensive and multidisciplinary care that integrates medical, pharmaceutical, physical, occupational, speech, nutrition, social, etc. therapies improves the quality of life of patients affected by ALS and their families, contributing to prologue the evolution of the disease (National Institute of Neurological Disorders and Stroke, 2013, Miguel Val’s Foundation, 2016).


The progressive and incapacitating nature of ALS, together with the fact that there is no cure, make it a difficult disease to manage. In addition to medical care, patients need emotional support from family, friends, physicians, and caregivers (The Journal American Medical Association, 2007).